Mouthpiece for presses for the manufacture of pipes and protecting-covers made of plastic materials.



Patented Mar. 26, [90L 0. HOFF MANN. MOUTRPIECE FOR PRESSES FOR THE MANUFACTURE OF PIPES AND PROTECTING COVERS MADE OF PLASTIC MATERIALS.

(Application filed Dec. 27, 1900.) (No Model.)

FIG. 2.

FIG. 3.

UNITED STATES PATENT OFFICE.

CARL I-IOFFMANN,'OF MAGDEBURG, GERMANY, ASSIGNOR TO FRIED. KRUPP GRUSONWERK, OF MAGDEB URC-BUCKAU, GERMANY.

MOUTHPIECE FOR PRESSES FOR THE lI/IANUFACTURE F PIPES AND PROTECTING-COVERS MAIJE 0F PLASTIC MATERIALS.

' SPECIFICATION forming part of Letters Patent No. 670,611, dated March 26, 1901.,

Application filed December 27, 1900. Serial No. 41,226.' (No model.)

To all whom, it may concern:

Be it known that I, CARL HOFFMANN, a subject of the King of Bavaria, and a resident of Magdebnrg, Kingdom of Prussia, Empire of Germany, have invented a new and useful Improvement in Mouthpieces for Presses for the Manufacture of Pipes and Protecting- Oovers Made of Plastic Materials, of which the following is a specification.

IO For making pipes of lead, gutt-a-percha, and

other plastic materials and fol-covering cables or other prismatic bodies with protecting-covers of these materials presses are employed .which press the plastic material contained in a receiver under high pressure by means ofone or several plungers through an annular aperture formed by a matrix and a mandrel, the section of which corresponds to dimensions of the pipe to be pressed. When making pipcs,this mandrel may be solid,while when covering cables and such like it is provided with an axial here to allow of the passage of the cables. With the mouthpiece used up to now, consisting of abev'eled hollow mandrel l and a circle-shaped matrix 2,as shown by Figure 4, these two formiuga concentric annular hole corresponding to the section of the pipe, there arise various inconveniences such as to render the manufacture of smooth and uniform pipes very diliicult; Inthe plastic but not liquid material the pressure does not continue in a uniform way, but the material is pressed the hardest on the side of the mandrel nearest the press-rams and is driven more rapidly through the annular aperture than at the opposite sides. Owing to this a pipe of irregular section is produced and upsetting takes place in the wall of the pipe, which causes the forming of wrinkles. Besides, the mandrel, which for thesake of solidity is of a pronounced beveled shape, causes the mater coming out of the mouthpiece to take the 'iireetionlof the generatrix of the bevel. (See Fig. 4.) The consequence is a strong 5 contraction of the material, by which'means the diameter of the pipe diminishes and upsetting and wrinkles occur in the pipe-walls.

By the present invention the above-mentioned inconveniences are avoided,the month e piece, consisting of 'hollow mandrel and ma- -.tiou of the arrangement.

trix, being formed in such a way that the material comes out with equal speed all around and takes a direction as parallel as possible to the axis of the mandrel. In order to -obtain this, a feeding-ring is placed before the g5 matrix, the bore of which is, however, not circular, but is made in such a manner that the play between the mandrel and this ring is widest at those spots of the month which are farthest away from the plnngers, while it gradually diminishes toward the spots nearest the plunger-s, where it is narrowest. Dering the operation the plastic material is at the narrower spots throttled more or less, according to its smaller or greater distance from the plungers, and thus forced to emerge from the mouth at an equalspeed. The con traction of the pipe-section is prevented in a simple manner by providing the beveled surface at'the end of the mandrel with a circular 7o flute, so that the material is forced to go out of the mouthpiece, taking a direction as parallel as possible to the axis of the mandrel. Figs. 1 to 3 show the above arrangements. Fig. 1 is a longitudinal section through the mandrel, the matrix, and the two receivers of a cable-press. The hollow mandrel 3 is screwed into the wall of the receiver 4:. In the opposite wall the feeding-ring 5 and the matrixfiare held in position by the matrixholder 7, screwed on. The space 8 serves as a chamber into which the plastic material is pressed out of the receivers 4 by the plungers 9 and from which it comes through the monthpiece either as a simple pipe or asa cover for a cable or for another prismatic body simultaneously conducted through theaperture of the mandrel. Fig. 2 is the cross-sec- In Fig. 1 the feeding-ring is cut at the points nearest the plun- 9o gers, and therefrom the annular space between mandrel and feeding-ring shows here its smallest section, while the cut, Fig. 2, is made through the two points of the annular space which are farthest away from the plun- 5 gers, and consequently have the largest crosssection.- Fig. 3 represents the upper view of the feeding-ring .and shows the varying diameter of the inner cavity. This ring may also be made in one piece with the matrix.

The bevel 10 ot the mandrel 3 is provided with the circular flute 11 in such a way that the tangent of the latteron the outlet runs in an almost parallel direction with the axis of the mandrel. Owing to this the inaterial deflects from the direction given by the bevel lO and takes the direction of the axis of the mandrel. The purpose 0 this arrangement is to avoid a diminution of the diameter of pipe required.

I claim- In order to obtain a uniform exit of the material taking the direction of the axis when using presses for the manufacture of pipes or protecting-covers of plastic materials, for cables or the like, the arrangement of a mouth- CARL HOFFMANN. In presence of-- WILHELM FLEISCHHAOK, M. J. BAEHR. 

